The exciting finding from our work with non-abrasive dusts is that there is both a physical and a physiological effect (it had previously been assumed that the effect was all physical), and that the latter is several times greater than the former. Such dusts afford a form of insect control albeit not widely used; we are trying to elucidate the nature of their lethal action. Since the physiological effect can be blocked by some metabolic inhibitors, it is proposed to check energy expenditure by measuring oxygen consumption under conditions at which dusts exert a lethal effect. Present data suggest that metabolically driven "pumps" are not involved but this must be made definite (all "pumps" are metabolically expensive, and either activation of inhibition of a "pump" should be reflected in oxygen consumption). Then there will be an examination of cell membranes and organelles to see if effects can be seen at the ultrastructure level. Present data also suggest that non-abrasive dusts give a stimulus that does not involve the central nervous system (not blocked by an anti-cholinesterase); but what is the stimulus? Is is transmitted from cell to cell and if so how? and why is the effect all-or-none? I plan to initiate studies to determine which of the membranes in and around the gut are permeability barriers. This will involve electron microscopy with markers such as ferritin and insects for which such data would be most interesting, namely fleas, mosquitoes, etc. (blood suckers which also transmit disease organisms). To finish up other unfinished work, mostly by electron microscopy, on the peritrophic membrane of mosquitoes, the proventriculus of mosquitoes and their relatives, the acanthae of fleas, and the anatomical peculiarities of the ventral diaphragm of flies. Also continue both kinetic and ultrastructural work on cryptobiosis in midge larvae.